* {
  padding: 0;
  margin: 0;
}
body {
  width: 100vw;
  height: 100vh;
  display: grid;
  justify-items: center;
  align-content: center;
}

.app {
  display: grid;
  border: solid 10px #333;
  position: relative;
  overflow: hidden;
}

.app div.box {
  border: solid 1px #ddd;
  box-sizing: border-box;
  color: #dcdcdc;
  display: flex;
  justify-content: center;
  align-items: center;
}

.app div.snake {
  position: absolute;
}
